SAVANNAH, Ga. – The three reservoirs on the Savannah River operated by the U.S. Army Corps of Engineers declared the first drought level Tuesday in response to the pool elevation at J. Strom Thurmond Lake dipping below 326.0 feet above mean sea level (ft-msl). Entering Trigger Level 1 activates the Corps’ drought management plan which conserves water in the reservoirs by reducing the outflows from the Thurmond Dam.
The pool elevations on Oct. 1 were 656.31 ft-msl at Hartwell Lake, and 325.48 ft-msl at Thurmond Lake. Under the existing drought plan, the Corps limits outflow from Thurmond Dam to a daily average of 4,200 cubic feet per second (cfs), when in Drought Trigger Level 1.
Water managers also adjust Hartwell releases as needed to stay in balance with Thurmond. Reducing outflow decreases the amount of hydropower generated through the dams but conserves more water in the reservoirs.
In addition, if the 28-day average stream flow at the Broad River gauge near Bell, Georgia, falls below 10 percent of normal, managers will further reduce the flow from Thurmond to a daily average of 4,000 cfs. The Corps expects the pools to stay in level 1 and continue their gradual decline through December.
Corps officials point out level 1 does not limit recreation on the reservoirs. While some swim beaches have limited water levels, camping, boating, skiing, fishing and other forms of recreation continue unabated.
As always, officials urge the public to use caution when boating, swimming or fishing. As the reservoir levels decline, underwater obstructions will be closer to the surface. This is particularly dangerous for boaters and skiers.
All visitors should wear a life jacket when swimming, boating or fishing. Dock owners may need to move their docks to remain in adequately deep water.
“The reservoirs stayed in normal operations and near or above full summer pool since October 2018,” said Stan Simpson, senior water manager for the Savannah District.
The reservoirs experienced a typical late summer decline, according to Simpson. Water managers and dam operators had previously reduced outflows from Thurmond Dam in September in order to balance pool levels between Hartwell Lake and Thurmond Lake.
The announcement of Trigger Level 1 indicates the reservoirs have essentially returned to balance. In addition, water managers will rely on increased pumpback operations at Russell Dam to help meet electricity demands and to retain water in the three-reservoir system.
Pumpback allows the Corps to generate electricity at the Russell Dam during peak afternoon demand times then reverse turbine direction at night to return the water for reuse the next day, providing power even during drought.
The congressionally authorized purposes of the reservoirs include water supply, water quality, recreation, flood risk management, navigation, hydropower production, and fish and wildlife management.
More than 10 public water systems and industrial users draw water directly from the reservoirs and even more draw from the Savannah River downstream of Thurmond Dam.
Downstream users include the cities of Augusta and Savannah in Georgia and North Augusta and Jasper County in South Carolina. Threatened and endangered species and the Savannah National Wildlife Refuge also depend on the river.
For more information on current lake levels and projections, contact the Savannah District Corporate Communications Office at 912-652-5014, or visit the District’s lake-level website.
~ Billy Birdwell, Corporate Communications Office